"He's a good public face for the BBC. I feel like I'm serving in the Royal Navy when the message came in: 'Winston is back.'"

"I think most people will be thrilled at this choice and [we] will also get the leadership that is needed from somebody who is a creative man and a good administrator - and a calm man in a time of crisis."

Tim Davie will remain as the acting director-general until Lord Hall is able to take up the post next March.

Lord Patten, chairman of the BBC Trust, said Lord Hall was the "right person" to lead the BBC as it takes "a long, hard look at the way it operates and put in place the changes required to ensure it lives up to the standards that the public expects".

The new DG - who was the only candidate contacted by the Trust - said: "It's been a really tough few weeks for this organisation and I know we can get through it by listening patiently by thinking carefully about what to do next."

Speaking at the BBC's Broadcasting House in London, he added: "I care passionately about the BBC, about what it can do, its programme-makers and the impact we have in all sorts of different ways.

"It's one of those extraordinary organisations which is an absolutely essential part of Britain, of the UK, of who we are. But also has this incredible impact around the world too.

"I know that with the right creative team in place, working off each other, sparking off each other, giving each other ideas, you can do extraordinary creative things and I want to build a world-class team for this world-class organisation."

The 61-year-old - made a cross-bench peer in 2010 - did not take questions from reporters about his appointment, and instead went to meet BBC staff.

Taking questions from reporters later, Lord Patten said: "I don't think that, given what has happened to the BBC in the last couple of months, it would have made any sort of sense for us to spend another four months going through a similar process to the one we went through before while we had an acting director-general, an acting head of news, an acting head of television and an acting head of radio.

"We had to move fast and I'm delighted that, in moving fast, we have also managed to find the out-and-out outstanding candidate.

"If we had to spend the next four months on this, you would all have been telling us we were off our trolleys and quite properly as well."

Lord Patten said the new director-general would have to pay close attention to its investigative journalism after the Newsnight controversy.

He said part of the director-general's top team would have to be "someone who is absolutely on top of the news and current affairs agenda - for all sorts of reasons".

He added: "All of you who work in newspapers know very well, for example, that managing investigative journalism is exceptionally difficult.

"So the sort of job that has been done by senior executives in the past is I think is one I think Tony will be thinking about very hard."

When one reporter suggested the BBC was becoming like Chelsea Football Club, which under owner Roman Abramovich has had eight managers in the last nine years, Lord Patten said: "We have had, unfortunately, two director-generals in the last nine years so it (the BBC) is some way behind Chelsea.

"I hope that this boss will win a few league titles and European competitions as well."

When asked about the severance package awarded to Entwistle, Lord Patten said the decision was taken after legal advice.

"The deal we did, while it may annoy for reasons I understand in headlines, was the best one for the BBC and for the licence fee- payer because anything else we would have done would have cost us more," he said.

"I haven't yet seen a single example of an employment lawyer who has argued against that.

"If you think it was easy you are kidding yourself.

"I have been in public life for a very long time, I'm not completely crazy.

"I knew perfectly well what newspaper headlines would say.

"I also knew what was in the interests of the BBC as an organisation and, above all, in the interests of the licence fee- payer."

Lord Hall will take over the £450,000 post after the resignation of former Director General George Entwistle

He added: "I look forward to saying that to the DCMS select committee if they ask me about it next week and I will also be telling them what I think about the legal advice we received and so on. I will have more to say about that then."

Lord Hall will have to rebuild the BBC's battered reputation after weeks of difficulties precipitated by the Jimmy Savile abuse scandal and a report on BBC2's Newsnight programme, which mistakenly implicated Lord McAlpine in child abuse.

That blunder led to Entwistle quitting his post and also saw the BBC settling with Lord McAlpine for £185,000 last week.

The direct approach for Lord Hall's recruitment is in marked contrast to the team of headhunters that was involved in drawing up the list of candidates which resulted in Entwistle, a BBC insider, being given the post.

Lord Patten said of the fast-track appointment, unanimously agreed by the trustees: "We might have considered going through the whole lengthy recruitment process again with a new round of advertisements and another global hunt for candidates.

"But I believe the approach we have taken is ultimately in the interests of the BBC and, most importantly, licence fee-payers as we have got the best candidate and he will help the organisation quickly get back on an even keel."

Birkenhead-born Lord Hall, who began as a news trainee with the BBC 39 years ago, is thought to have been in the running for the director-general post when Greg Dyke was appointed in 1999. He was not an applicant when the position was vacated by Mark Thompson earlier this year.

Tony Hall, the former chief executive of the Royal Opera House in London, with the Queen

Lord Hall, who was head of BBC news and current affairs from 1996 to 2001, acknowledged it had been a "difficult few weeks" but said he wanted to lead a "world-class BBC".

He said: "This organisation is an incredibly important part of what makes the United Kingdom what it is. And, of course, it matters not just to people in this country, but to tens of millions around the world too.

"It's been a difficult few weeks - but together we'll get through it. I'm committed to ensuring our news services are the best in the world.

"I'm committed to making this a place where creative people, the best and the brightest, want to work."

Lord Hall is credited with turning around the fortunes and public perception of the once troubled Royal Opera House.

Simon Robey, who chairs the ROH's board of trustees, said: "I can think of nobody better able to bring stability back to the BBC. They see, as we do, his qualities of leadership and his depth of relevant experience."